In 1976, the Supreme Court upheld most of those post-Watergate limits for federal candidates. But lately, the court has thumbed its nose at that history and reversed course. It struck down the Montana and Arizona laws, and opened the way for unlimited independent spending by corporations and labor unions in its 2010 Citizens United decision. An appeals court similarly allowed unlimited spending by wealthy individuals, which is how billionaire casino owner Sheldon Adelson was able to give at least $70 million to Super PACs supporting Newt Gingrich, Mitt Romney and other Republicans last year.

Maybe not compared with Adelson's $70 million, but it's a safe bet that many a member of Congress would jump to take a phone call from anyone who gave that much to help hold his party's majority.

In constitutional terms, this is not an easy issue. The numbers are unavoidably arbitrary. It's impossible to precisely define a corrupting amount and difficult to come up with a number sufficient for free speech. The current limits even feel quaint compared with the millions of dollars flowing to independent Super PACs. But money that goes directly to candidates, parties or PACs is more problematic. It has greater potential to create a sense of obligation to pay back the donor — even if it's not an outright payoff.

The public should have a right to protect itself from such things through the political process, something the court seems entirely too eager to usurp.

History says the outcome — corruption — is not in doubt. In time, irate voters may decide that public financing and full disclosure are effective routes to good government. Both have passed the court's scrutiny. But until that happens, limits on donations remain a bulwark against bribery, legal and otherwise. The court would be wise to leave them in place.

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